Heavy metals in wastewater: Their removal through algae adsorption and their roles in microwave assisted pyrolysis of algae.

Abstract

Chlorella vulgaris was found as a good biosorbent for copper, zinc and aluminum. pH value, reaction time, initial metal and algal sorbents concentrations were considered as parameters affecting metal removal efficiency. In appropriate conditions, 85% of copper(II), 70% of zinc(II) and 99% of aluminum(III) could be removed from solutions by tested microalgae within 20 minutes. In following pyrolysis of the algae, metals were further concentrated in the charcoal. 96.17% of Copper and 97.34% of Zinc stayed in the char portion. Metals in the algal feedstock improved the bioenergy production during microwave assisted pyrolysis of the algae by reducing heating time to about half of before. The presence of metals also significantly decreased the nitrogen containing compounds and the carbon dioxide output and increased the aromatics generation.